Gas turbine combustors generally may be formed from annular combustors or can combustors. Annular combustors include a combustor chamber that is formed from a plurality of removable liners. The removable liners are exposed to extreme heat during operation, which often causes distortions and failure in liners. Thus, the liners are replaced at regular intervals to prevent such failure from occurring during operation.
The liners are often removably coupled to a carrier, which forms the support structure of the combustor, using either spring clips or bolted configurations. Spring clips couple liners to each other and to the carrier of a combustor. However, spring clips often suffer from relaxation and creep after being exposed to high temperatures commonly found in a combustor chamber, which can result in loss of clamp force in the clips. As a result, spring clips and liners can be liberated during operation of a combustor and cause substantial damage to a turbine engine. To prevent damage, spring clips often must be replaced frequently.
Combustor liners may be coupled to a carrier using either a hot side bolted method or a cold side bolted method. The hot side bolted method involves bolting liners to a carrier by inserting bolts through orifices in the liners from the hot side of the combustor, that is, the inner aspects of the combustor where combustion occurs. Liners installed in this manner may be removed by personnel entering the inner aspects of the combustor through a manhole or other device and loosing the bolts attaching the liners to a carrier. While liners attached to a carrier in this manner may be removed easily, this method of attachment has disadvantages and risks. For instance, should the bolts loosen during operation, the bolts pose a threat of becoming disengaged from the carrier and traveling downstream into turbine blade assemblies. In addition, the bolts are exposed to hot gases in the combustor chamber and consequently must be cooled and made from expensive alloys. Air supplied from the compressor of the turbine combustor is often used to cool the bolts; however, use of compressor supplied air increases nitrous oxide emissions and degrades turbine combustor performance.
The cold side bolted method involves using bolts installed from the cold side of the combustor, that is, the outside surface of the combustor. The bolts are passed through the carrier and are received by the liners. Installing bolts in this method alleviates the possibility of bolts loosening and traveling downstream and alleviates the need to cool the bolts. If a cold side coupled bolt were to loosen and become detached from the liner, the bolt would fall outside of the combustion cavity and, therefore, pose no threat of harm to the turbine assemblies. However, a significant disadvantage of the cold side bolted method is the amount of time needed to access the bolts to remove and replace the liners. The bolts may not be accessed from the inner aspects of the turbine combustor. Instead, the bolts typically may only be accessed after an engine casing has been lifted, which may take hours or weeks.
Thus, a need exists for a more efficient system and method for releasably attaching combustor liners to carriers.